<template>
  <div class="spec-preview">
    <img :src="skuImage.imgUrl" />
    <div class="event" @mousemove="handler"></div>
    <div class="big">
      <img :src="skuImage.imgUrl" ref="big"/>
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuImageList"],
  data() {
    return {
      curIndex: 0,
    };
  },
  mounted() {
    this.$bus.$on('changeImg', (index) => {
      console.log(index);
      this.curIndex = index;
    });
  },
  computed: {
    skuImage() {
      return this.skuImageList[this.curIndex] || {};
    },
  },

  methods: {
    handler(event){
      //获取元素
      let mask = this.$refs.mask;
      let big = this.$refs.big;
      let width = mask.offsetWidth;
      let height = mask.offsetHeight;
      let left = event.offsetX - width / 2;
      let top = event.offsetY - height / 2;
      //约束范围
      if(left < 0) left = 0;
      if(top < 0) top = 0;
      if(left > width) left = width;
      if(top > height) top = height;
      //修改元素
      mask.style.left = left + 'px';
      mask.style.top = top + 'px';
      big.style.left = - 2 * left + 'px';
      big.style.top = - 2 * top + 'px';
    }
  }
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>